Clutch mods

oldman · Jul 13, 2011

High Norton chaps has anyone done a hydraulic clutch conversion or changed the clutch basket etc ?
I have searched but could not find anything
My clutch is a bit heavy (understatement) compared to my other bikes its on a 750

Thanks for any replies or even a link to an old thread

DogT · Jul 13, 2011

I have seen reports of the hydraulic clutch, but can't comment. There is no reason your standard 750 clutch should be any problem unless it's not set up right or there is some issue with parts. My 67 year old hand with median nerve damage from my neck pulls it just fine. If it feels like something breaks over (gets lots lighter) just before you have it against the handle, it's fine.

Dave
69S

AussieCombat · Jul 13, 2011

Yes oldman, check the threads, your Commando clutch should be like butter.
They need to be fine tuned as they wear. Check the cable first.

rx7171 · Jul 13, 2011

oldman said:
High Norton chaps has anyone done a hydraulic clutch conversion or changed the clutch basket etc ?
I have searched but could not find anything
My clutch is a bit heavy (understatement) compared to my other bikes its on a 750

Thanks for any replies or even a link to an old thread

I also had a very hard pull on my clutch when I got the bike.
It appears the clutch stack was too low, possibly from friction plate wear.
OldBritts offer plain shim plates that can be added to the stack that reduces the pull pressure needed.
I used the 0.060" thick one and now its a two finger pull and I've never been able to make the clutch slip.
Here is info from OldBritts site.

Also confirm clutch cable has minimal bends.
I also use a teflon lined one from Venhill.

>>Shim plain plates (part # 06-0745/075, $35.00 each) are approximately .075" thick.
Shim plain plates (part # 06-0745/070, $35.00 each) are approximately .070" thick.
Shim plain plates (part # 06-0745/065, $35.00 each) are approximately .065" thick.
Shim plain plates (part # 06-0745/060, $35.00 each) are approximately .060" thick.
The shim plates are stock plates that we have precision ground on both sides to guarantee a true flat plate.

Adjusting the clutch pull:

The clutch pull (hard or easy) is determined by where the total thickness of the clutch plate stack is from the clutch spring circlip grove. In the above picture, you can see that the total stack is well below the circlip grove, which means that the diaphragm spring has to be pulled beyond its center making the clutch pull hard. This clutch would take an extra plain plate between the last friction plate and the pressure plate. The .065" thick plain plate put the stack at just the correct position. On my MK3 I forgot to put the correct shim plate in one time and a trip through traffic about ruined my hand it was so hard to pull. I actually added one Barnett plane plate to achieve the correct thickness. Since it is hard to measure the distance the stack is below the circlip grove, we will let you purchase one each plain plate, find the one that fits and send the rest back for full refund. That is as long as you do not damage the plates and are willing to pay shipping back to Old Britts. <<

lrutt · Jul 14, 2011

I had real clutch problems on my 73 850. heavy pull, not fully disengaging. No matter what I could not get it adjusted. The stack hieght was tweaked in and everything. So as a last resort I pulled the POS barnett plates and went back to the original style bronzed plates. Problem solved. Easy pull, no drag, just the way it should be.

lukeya · Jul 14, 2011

Good grief, I've tried everything.

I have a hydraulic conversion from CNW, used bronze plates but suffered from slip badly (esp. over 90 mph) so am using Barnett plates now. No slip at all.

Hydraulic kit is OK but does not really produce a lighter clutch - a little unfortunately. CNW do a clutch pack that produces the correct height and Old Britts do the same i Think.

L

pete.v · Jul 14, 2011

rx7171 said:
[
Adjusting the clutch pull:

The clutch pull (hard or easy) is determined by where the total thickness of the clutch plate stack is from the clutch spring circlip grove. In the above picture, you can see that the total stack is well below the circlip grove, which means that the diaphragm spring has to be pulled beyond its center making the clutch pull hard. This clutch would take an extra plain plate between the last friction plate and the pressure plate. The .065" thick plain plate put the stack at just the correct position. On my MK3 I forgot to put the correct shim plate in one time and a trip through traffic about ruined my hand it was so hard to pull. I actually added one Barnett plane plate to achieve the correct thickness. Since it is hard to measure the distance the stack is below the circlip grove, we will let you purchase one each plain plate, find the one that fits and send the rest back for full refund. That is as long as you do not damage the plates and are willing to pay shipping back to Old Britts. <<[/color]

This is the way to go. Although a fresh pack my bring this height to spec, it may still need fine tuning. Generally just by adding an extra drive plate will do the trick and may add another 5000 mile the the clutch pack. A stock plate is fairly cheap and handy.

MelloYellow · Jul 14, 2011

Changing to a new, teflon lined cable made a huge improvement for my 1970 -
MelloYellow

Reggie · Jul 14, 2011

oldman wrote;

My clutch is a bit heavy (understatement) compared to my other bikes its on a 750

Also check the clutch centre for "notching." The bronze plates are worse for causing this.
I've fitted surflex plates on mine a popped an extra plain steel plate in but am using the 850 pressure plate which I believe is thinner than the standard 750 suflex based clutch.
The stack now sits just below the circlip with the diaphragm on. Mines quite light.

Basically as has been said, sensible cable routing with a correct stack height should give quite a light clutch.

Clutch mods

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